Integral Abutment Connections with Grouted Reinforcing Bar Couplers and Ultrahigh-Performance Concrete

Use of precast elements in the design and construction of bridges, especially for accelerated bridge construction (ABC), has been gaining traction to minimize the impact of closures resulted from cast-in-place construction. One such element being investigated is the integral abutment. This is to eliminate the need for expansion joints between the substructure and the superstructure, where the penetration of water and deleterious agents can cause long-term performance issues. The integral abutment alleviates the need for an expansion joint by having the superstructure rigidly connected to the foundation, ensuring that they act together in response to traffic loads, as well as thermal expansions and contractions. Due to this connection needing to be heavily reinforced, congestion issues often arise. Moreover, the construction tolerance and weight of the integral abutment can introduce practical challenges. Addressing such issues, especially for ABC applications, was the main motivation for the current study, in which two novel integral abutment connection details were investigated. The developed details included grouted reinforcing bar couplers, along with normal-strength and ultrahigh-performance concrete materials for the joint. As a control specimen, a cast-in-place integral abutment was investigated as well. The performance of the connection details was evaluated through full-scale laboratory tests, in which simulated thermal and live loads were applied to the specimens. A complementary set of three-dimensional finite-element simulations were also conducted to further extend the findings obtained from the laboratory experiments. This was with a focus on the couplers and how they contribute to the structural response. The outcome of this study provides original information, particularly to improve the connection details used in integral abutments.